FEATURE: Basic backend support for muted and watched categories

app/models/category_user.rb

@@ -0,0 +1,49 @@
+class CategoryUser < ActiveRecord::Base
+  belongs_to :category
+  belongs_to :user
+
+  # same for now
+  def self.notification_levels
+    TopicUser.notification_levels
+  end
+
+  def self.auto_watch_new_topic(topic)
+    apply_default_to_topic(
+                           topic,
+                           TopicUser.notification_levels[:watching],
+                           TopicUser.notification_reasons[:auto_watch_category]
+                          )
+  end
+
+  def self.auto_mute_new_topic(topic)
+    apply_default_to_topic(
+                           topic,
+                           TopicUser.notification_levels[:muted],
+                           TopicUser.notification_reasons[:auto_mute_category]
+                          )
+  end
+
+  private
+
+  def self.apply_default_to_topic(topic, level, reason)
+    # Can not afford to slow down creation of topics when a pile of users are watching new topics, reverting to SQL for max perf here
+    sql = <<SQL
+    INSERT INTO topic_users(user_id, topic_id, notification_level, notifications_reason_id)
+    SELECT user_id, :topic_id, :level, :reason
+    FROM category_users
+    WHERE notification_level = :level AND
+          category_id = :category_id AND
+          NOT EXISTS(SELECT 1 FROM topic_users WHERE topic_id = :topic_id AND user_id = category_users.user_id)
+SQL
+
+    exec_sql(
+        sql,
+                  topic_id: topic.id,
+                  category_id: topic.category_id,
+                  level: level,
+                  reason: reason
+
+            )
+  end
+
+end

app/models/topic_user.rb

@@ -20,7 +20,15 @@ class TopicUser < ActiveRecord::Base
     end
 
     def notification_reasons
-      @notification_reasons ||= Enum.new(:created_topic, :user_changed, :user_interacted, :created_post, :auto_watch)
+      @notification_reasons ||= Enum.new(
+        :created_topic,
+        :user_changed,
+        :user_interacted,
+        :created_post,
+        :auto_watch,
+        :auto_watch_category,
+        :auto_mute_category
+      )
     end
 
     def auto_track(user_id, topic_id, reason)

db/migrate/20140101235747_add_category_users.rb

@@ -0,0 +1,9 @@
+class AddCategoryUsers < ActiveRecord::Migration
+  def change
+    create_table :category_users do |t|
+      t.column :category_id, :integer, null: false
+      t.column :user_id, :integer, null: false
+      t.column :notification_level, :integer, null: false
+    end
+  end
+end

lib/topic_creator.rb

@@ -22,17 +22,23 @@ class TopicCreator
     save_topic
 
     watch_topic
+    auto_mute_topic
 
     @topic
   end
 
   private
 
+  def auto_mute_topic
+    CategoryUser.auto_mute_new_topic(@topic)
+  end
+
   def watch_topic
     unless @opts[:auto_track] == false
       @topic.notifier.watch_topic!(@topic.user_id)
     end
     TopicUser.auto_watch_new_topic(@topic.id)
+    CategoryUser.auto_watch_new_topic(@topic)
   end
 
   def setup

spec/models/category_user_spec.rb

@@ -0,0 +1,31 @@
+# encoding: utf-8
+
+require 'spec_helper'
+require_dependency 'post_creator'
+
+describe CategoryUser do
+  context 'integration' do
+    before do
+      ActiveRecord::Base.observers.enable :all
+    end
+
+    it 'should operate correctly' do
+      watched_category = Fabricate(:category)
+      muted_category = Fabricate(:category)
+      user = Fabricate(:user)
+
+      CategoryUser.create!(user: user, category: watched_category, notification_level: CategoryUser.notification_levels[:watching])
+      CategoryUser.create!(user: user, category: muted_category, notification_level: CategoryUser.notification_levels[:muted])
+
+      watched_post = create_post(category: watched_category)
+      muted_post = create_post(category: muted_category)
+
+      Notification.where(user_id: user.id, topic_id: watched_post.topic_id).count.should == 1
+
+      tu = TopicUser.get(muted_post.topic, user)
+      tu.notification_level.should == TopicUser.notification_levels[:muted]
+      tu.notifications_reason_id.should == TopicUser.notification_reasons[:auto_mute_category]
+    end
+
+  end
+end

spec/support/helpers.rb

@@ -28,6 +28,7 @@ module Helpers
     args[:title] ||= "This is my title #{Helpers.next_seq}"
     user = args.delete(:user) || Fabricate(:user)
     guardian = Guardian.new(user)
+    args[:category] = args[:category].name if Category === args[:category]
     TopicCreator.create(user, guardian, args)
   end
 
@@ -36,6 +37,7 @@ module Helpers
     args[:raw] ||= "This is the raw body of my post, it is cool #{Helpers.next_seq}"
     args[:topic_id] = args[:topic].id if args[:topic]
     user = args.delete(:user) || Fabricate(:user)
+    args[:category] = args[:category].name if Category === args[:category]
     PostCreator.create(user, args)
   end